India need not take an aggressive position in public on the issue of US sanctions on nations defying its directive to bring their oil imports from Iran to zero by November 4, says a former Indian diplomat.

India has to play a cautious role, in that priority should be the country's national interests, former Ambassador of India to Saudi Arabia Oman and the UAE Talmiz Ahmad said.

"India's national interests lie in maintaining relations with Iran while at the same time not totally alienating the United States", he told PTI.

"And what India will do and I think that's the correct policy that there will be some reduction in oil imports for a short period and at the same time discussions with the United States will continue in order to ensure that the US policy becomes more accomodative", Mr Ahmad said.

He was of the view that over a period of time or as early as six months, the entire sanctions regime would "collapse".